1. Field of the Invention
The present invention relates to a method of manufacturing a magnetic head which is capable of improving controlling a thickness of a gap layer.
2. Description of the Related Art
Generally, an inductive head for recording a magnetic signal on a recording medium has a structure in which it includes a first magnetic layer and a second magnetic layer that are opposite to each other in a film thicknesswise direction at a surface facing the recording medium with a gap layer interposed therebetween, and a coil layer that is provided between the first magnetic layer and the second magnetic layer at a location farther than the facing surface in a heightwise direction.
FIG. 15 is a diagram illustrating one process of a method of manufacturing a conventional perpendicular magnetic recording head. In addition, FIG. 15 is a partial longitudinal cross-sectional view of the conventional perpendicular magnetic recording head.
As shown in FIG. 15, reference numeral 1 indicates a shield layer. On the shield layer 1, lower coil pieces 3, which form a helical coil with a coil insulating layer 2 interposed between the shield layer 1 and the lower coil pieces 3, are formed in a plurality of columns. One end of a lower coil piece 3a among the lower coil pieces 3, which is formed so as to be closest to the surface F facing the recording medium, and one end of the lower coil piece 3b among the lower coil pieces 3, which is formed so as to be farthest from the surface F facing the recording medium in a heightwise direction (Y direction in the drawing), extends more than the other lower coil pieces 3 so as to form a coil lead layer 4. As shown in FIG. 15, a conductive contact layer 5 is formed on the coil lead layer 4, and a surface of the conductive contact layer 5 is exposed to a surface of a coil insulating layer 6 for covering the lower coil pieces 3.
As shown in FIG. 15, a main magnetic pole layer 7 and an auxiliary yoke layer 8 are sequentially formed on the coil insulting layer 6. As shown in FIG. 15, the auxiliary yoke layer 8 is formed so as to retreat more than the facing surface F in a heightwise direction (Y direction in the drawing), and a non-magnetic gap layer 9 is formed on the main magnetic pole layer 7 exposed to the facing surface F and the auxiliary yoke layer 8. As shown in FIG. 15, a Gd determining layer 10 and an insulating base layer 11 are formed on the gap layer 9. A plurality of upper coil pieces 13 are formed on the insulating base layer 11 in a plurality of columns. The plurality of upper coil pieces 13 form a helical coil with a plurality of conductive coil base layers 12 interposed between the insulating base layer 11 and the upper coil pieces 13. As shown in FIG. 15, the upper coil pieces 13 are covered with a coil insulating layer 14 made of resist or the like.
As shown in FIG. 15, before the process proceeds to a process illustrated in FIG. 16, a surface of the contact layer 5 exposed to the surface of the coil insulating layer 6 is etched, and an oxide layer formed on the surface of the contact layer 5 is removed (cleaning process). The contact layer 5 is formed of a material, such as Cu or the like, which has excellent conductivity, but it is likely to be oxidized. In addition, the coil base layer 12 is first formed on the contact layer 5. Then, the unnecessary coil base layers 12 are removed by an etching process, except for the coil base layers 12 formed below the upper coil pieces 13. However, in this case, the coil base layer 12 formed on the contact layer 5 may not be removed by the etching process, and may remain on the contact layer 5. Even in this case, since the coil base layer 12 has a laminated structure between Cu and Ti and an oxide layer is easily formed on the coil base layer 12, it is required to perform a cleaning process for removing the oxide layer of the surface of the contact layer. As shown in FIG. 16, the cleaning process is necessary for implementing conductivity between the contact layer 5 and a conductive lifting layer 17 formed on the contact layer 5. In addition, the reason why the oxide layer is formed is as follows. In the process illustrated in FIG. 16, when a magnetic head is carried in a sputtering device in the middle of a process of forming a return yoke base layer 16 on the gap layer 9 exposed to the facing surface F and the coil layer 14 by using a sputtering method before forming a return yoke layer 15 by plating, it may be easily affected by the air. In addition, when the coil insulating layer 14 is formed, oxide may occur due to a patterning process such as exposure, development, or the like or a hardening heating process.
Accordingly, as described above, the etching process is performed so as to remove the oxide layer formed on the surface of the contact layer. However, as shown in FIG. 15, since the gap layer 9 is exposed to the facing surface F ahead of the Gd determining layer 10, the gap layer 9 is also affected by the etching process. As a result, as shown in FIG. 17, the thickness H1 of the gap layer 9 becomes smaller than the original thickness H2. As such, in the conventional method of manufacturing the magnetic head, since deviation may occur in the thickness of the gap layer 9, it is not possible to properly control the thickness of the gap layer 9.
As shown in FIG. 17, the Gd determining layer 10 formed on the gap layer 9 is provided so as to regulate a gap depth (Gd). However, the surface 10a of the Gd determining layer 10 is affected by the etching process, so that the surface 10a is cut as shown by a dot line in FIG. 17, thereby varying the gap depth (Gd). In addition, after the surface 10a is cut, the gap layer 9 may be further affected by the etching process, so that the gap layer 9 may be further cut. In particular, the influence of the etching with respect to the gap layer 9 below the Gd determining layer 10 varies by a shape of the surface 10a of the Gd determining layer 10 or to what extent the surface 10a is affected by the etching process. Therefore, it is likely for the shape of the gap layer 9 not to be uniform.
In U.S. Pat. No. 6,490,128 and US Publication No. 2003/0165030, the above-mentioned problems are not described. Therefore, countermeasures for resolving the above-mentioned problems are also not suggested. For example, according to a method disclosed in U.S. Pat. No. 6,490,128, an ion milling process is performed so as to remove an oxide layer in a process illustrated in FIG. 7 (column 12, line 66 to column 13, line 6), but a gap layer 28a is affected by the ion milling process.